Question

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$Describe \: Bohr's \: model \: of \\ the \: atom.$
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Answer 1

Bohr's model of an atom:-

The Bohr's model is a quantum-physics-based modification of the Rutherford model.It explains the reason for the structure of the Rydberg formula and also provided a justification for its empirical results in terms of fundamental physical constants.

According to Bohr's theory,

✦The atom consists of a small positively charged nucleus at its centre.

✦The nucleus consists all protons & neutrons of the atom.

✦ The whole mass of the atom is concentrated at the nucleus.

✦The volume of nucleus is smaller than the volume of the atom by a ratio of about 1:10.

✦The electrons of the atom revolve round the nucleus in fixed circular paths calleds orbits.

✦Each orbit is associated with a fixed amount of energy. Therefore, these orbits are also known as energy levels or energy shells.

✦These energy levels are designated as K, L, M, N or numbered as n=1,2,3,4  from the side of nucleus.

✦As long as the electron revolves in an orbit,it neither looses nor gain energy.So the energy of an electron remains constant.Hence,these orbits are called stationary orbits.

✦The angular momentum of an electron is always an integral multiple of h/2π.It is given by,

  ★ mvr = nh/2π

Where,

• m = mass of electron
• v = velocity of electron
• r = radius of an orbit
• h = plank's constant
• n = principle quantum number

✦If an electron jumps from one level to another level,it may emit or absorb energy.

   ★ΔE = E₂- E₁ = hυ

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Answer 2

Question:-

1. Describe Bohr's model of atom?

Answer:-

    To overcome the drawback of Rutherford's model, Neils bohr, in 1913 gave an arrangements of electrons in atom.

According to him,

• The electrons could revolve around in fixed orbits around the nucleus where each orbit has a different radius.
• The electron does not radiate energy while revolving even after having motion around the nucleus.